1. Field of the Invention
The present invention generally relates to electronic devices to be placed in a high temperature environment, such as an automobile engine compartment, particularly it relates to a terminal unitarily assembled with a ceramic element of the electronic components, such as an oxygen sensor, a NOx sensor, a CO sensor, a CO.sub.2 sensor, a heat sensor, a ceramic heater, and a ceramic glow plug placed in a high temperature gas environment, for instance, an exhausted gas from automobile vehicle engines.
Specifically, this invention relates to a electronic component of a miniature size having a ceramic element unitarily connected to metal wire leads, the electronic component assembly withstanding the gas environment from an ambient temperature up to a high temperature of 800.degree. C.
This invention further relates to a method of assembling parts, such as a ceramic element and leads, into a unitary electronic component to be used at the high temperature, minimizing the number of the parts.
2. Description of the Related Art
Many high-temperature components are required in a high temperature periphery of vibrant automobile engines. These components include oxygen sensors, NOx sensors, and heat sensors that are placed in exhaust pipes of internal combustion engines.
These electrical control components output electrical signals to a computer control circuit through resin-covered metal wires. These resin covered metal wires do not withstand the high temperature of more than 300.degree. C.
In order to connect these low temperature resistant wires with a ceramic element of the electrical component for high temperature use, conventionally a terminal assembly as shown in FIG. 21 referring as a Related Art of the Invention has been recommended.
Referring to this terminal assembly of the Related Art, a high temperature ceramic element 150 is electrically and mechanically connected to sheathed lead wires 152 via metal leads 153. Electrodes 151 formed on the ceramic element 150 are contacted with the metal leads 153. Two ceramic plates 154 having notches insulate the metal leads 153 from a metal fastener 157 by covering the metal leads 153. Two half pipes 155 having a U shape in cross section hold the ceramic plate 154 therein.
A spring plate 156 having a triangle shape in cross section is attached on an outer side of the each half pipe. The tubular metal casing 157 presses in the metal leads 153, the ceramic plates 154, the half pipes and the spring plates 156 in a radial direction, aligning them and forming a terminal assembly unit. In this terminal assembly unit, the metal lead 153 has a J shape portion which bends like a spring and sit in the notch of the ceramic plate 154 to hold the element when the ceramic element slides into the unit and the spring plates 156 also press the ceramic plates in. These metal leads 153 form a female connecting portion which receives the electrodes 151 of the ceramic elements 150 and clamps the ceramic elements 150 with a strong fastening pressure given from the spring plates 156.